Reduction of HMF ethers with metal catalyst

ABSTRACT

Methods of making reduced derivatives of hydroxymethyl furfural using metal catalysts are described. The derivatives may have tetrahydrofuran or furan nucleus with alkoxymethyl ether or ester moieties on the 5′ carbon and methanol on the 2′ carbon. Suitable metal catalyst include Raney nickel, a nickel catalyst with a zirconium promoter, a chromite catalyst with a barium, a palladium catalyst, such as palladium on carbon, or a ruthenium catalyst. Also provided are a new class of compounds, which are n-alkoxy hexane diols (i.e., 1,2 or 1,5 hexane diol ethers) and methods of making the same by reduction of furan or tetrahydrofuran derivatives.

PRIORITY CLAIM

This application is a divisional application of prior, co-pending U.S.application Ser. No. 13/096,348 filed Apr. 28, 2011, and claims priorityto PCT Application Serial No. PCT/US2009/062778 filed Oct. 30, 2009,which itself claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Application Ser. No. 61/109,634, filed Oct. 30, 2008, whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

This disclosure relates to methods of reducing hydroxymethylfurfuralderivatives. More particularly, this disclosure relates to methods ofreducing hydroxymethylfurfural ethers and hydroxymethylfurfural esterswith hydrogen in the presence of a metal catalyst to produce5-(alkoxymethyl)-tetrahydrofuran-2-methanol or5-alkoxymethyl)-furan-2-methanol derivatives and purification thereof.In addition, the disclosure relates to n-alkoxy hexane diol compounds,which are derivative compounds useful for replacement of petroleum basedcarbitol compounds that can be made from the reducedhydroxymethylfurfural ethers made according to the methods of thepresent disclosure.

BACKGROUND

The use of naturally derived material as starting materials andintermediates for commercial products is a growing industry. Forexample, a great deal of research is being conducted to convert naturalproducts into fuels as a cleaner alternative to fossil-fuel based energysources. Agricultural raw materials such as starch, cellulose, sucroseor inulin are inexpensive and renewable starting materials for themanufacture of hexoses, such as glucose and fructose. Fructose, anabundant compound derived from natural products such as corn, may beconverted to other materials, such as hydroxymethylfurfural, or HMF, andits related ethers.

One desirable derivative of HMF ethers is a partial reduction productwhich converts the aldehyde moiety of HMF to an alcohol. Although thereis no known method for the reduction of HMF ethers, one method ofreducing aldehydes to alcohols is described by Eller et al. in U.S. Pat.No. 6,350,923. This method uses a metal catalyst, such as nickel, cobaltor copper, reacted with the aldehydes at elevated temperatures andpressures. However, the method does not mention the ability of thecatalyst to reduce a C═C bond.

Methods used to synthesize products that are similar to HMF ethers arealso inadequate in terms of yield and use of undesirable reactants. Forexample, a method of synthesizing an equivalent of an HMF etherderivative without the use of HMF as a starting material is described byPevzner et al. (Zhurnal Organicheskoi Khimii (1987), 23(6), 1292-4). Inthis method, an alkyloxymethylfuran is reacted with paraformaldehyde at70-80° C. for 3 hours to give 2-hydroxymethyl-5-alkyloxymethylfuran.However, the yield was poor 55%, and in addition, the reaction requiresthe use of paraformaldehyde, a known irritant to the respiratory systemand skin.

The product guide for G-693 nickel on kieselguhr with zirconium promotercatalyst (Sud Chemie) lists the catalyst as useful for reduction ofterpenes, which contain C═C bonds. However, as is well known in the art,the furan ring in HMF, which contains two conjugated C═C bonds, is muchmore difficult to reduce than non-conjugated C═C bonds. Furthermore, theguide does not mention the ability of the catalyst to reduce aldehydes.

The present disclosure addresses the shortfalls of the prior art andprovides methods for reducing the aldehyde and/or C═C bond of HMF ethersto the resulting alcohol and C—C bond, respectively, at high yields.

SUMMARY OF THE DISCLOSURE

In one aspect, the present disclosure provides methods of reducing HMFethers and esters with hydrogen in the presence of a metal catalyst toproduce 5′ alkoxy substituted furans or tetrahydrofurans or, 5′acylmethyl substituted furans or tetrahydrofurans in the case of esters.Also proved are derivatives of such compounds and uses for suchcompounds. Also provided are bio-based compositions comprising suchcompounds as determined by ASTM International Radioisotope StandardMethod D 6866.

In another aspect the present disclosure provides for derivativecompositions that can be made from the hydrogenated HMF ethers andesters and methods of making the same. In certain embodiments thederivative compositions, like the starting compositions, are useful assolvents, cross-linking and grafting reagent and the disclosure providesfor ways of using said compositions as bio-based renewable substitutesfor petroleum based compositions, including in certain exemplaryembodiments, substitutes for petroleum based carbitol solvents.

Embodiments of methods of making the forgoing compounds include,contacting a hydroxymethyl furfural 5′ R ether or ester, where R is analkyl group of 1 to 5 carbons, with a metal catalyst capable of reducingthe furfural compound in the presence of hydrogen. In one embodiment,the catalyst is a nickel catalyst such as Raney Nickel. In anotherembodiment the catalyst is a nickel catalyst with a zirconium promoterexemplified by the product G-69B available from Sud Chemie. In yetanother embodiment the catalyst is can be a chromite catalyst with abarium promoter exemplified by the product G-22 also available from SudChemie. In yet another embodiment the catalyst can be a palladiumcatalyst, such as palladium on carbon exemplified by the catalyst Pd/C.In yet another embodiment the catalyst can be a ruthenium catalyst. Intypical embodiments, the hydrogenation is conducted, at a temperature, apressure and a time sufficient to convert at least 40% of the 5′ alkoxyhydroxymethyl furfural to the (5′ alkoxy)-furan or tetrahydrofurancompositions mentioned above. In other embodiments at least 80% of the5′ alkoxy hydroxymethyl furfural is converted to the 5′ alkoxy furan ortetrahydrofuran

Another aspect is use of the forgoing 5′-alkoxy or 5′acylmethyl-furan ortetrahydrofurans and/or derivatives thereof as bio-based replacementsfor petroleum based solvents.

Another aspect is a new class of n-alkoxy hexane diols of the formula:

wherein R may be is an alkyl group of 1 to 24, or more typically 1-5,carbons, which are made by further contacting the foregoing(5-alkoxymethyl)-furan-2-methanol or(5-alkoxymethyl)-tetrahydrofuran-2-methanol compounds with hydrogenationcatalyst, preferably a Ni catalyst, for a time sufficient to open thering of the furan or tetrahydrofuran derivative.

These alkoxy hexane diol compounds are useful as solvents that cansubstitute for petroleum based glycol ether solvents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows aminated alkoxy tetrahydrofuran or furan starch derivativesmade possible by certain embodiments of the invention.

FIG. 2 shows a GC/MA chromatogram of products made in accordance withExample 7.

FIG. 3 shows a GC/MA chromatogram of products made in accordance withExample 9.

FIG. 4 shows a GC/MA chromatogram of products made in accordance withExample 10.

FIG. 5 shows a GC/MA chromatogram of products made in accordance withExample 11.

FIG. 6 shows a GC/MA chromatogram of products made in accordance withExample 20.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides methods for reducinghydroxymethylfurfural (HMF) ethers and esters and provides forderivatives that can be made therefrom. It also provides for a novelclass of such compounds defined at least in part because these compoundsmeet the standards for industrial chemicals derived from renewableresources rather than petroleum based resources. The bio-based compoundsof the present invention can be used as substitutes for similar oridentical compounds derived from petroleum based resources.

There are known methods for determining the bio-based content, thereforedetermining whether organic compositions are obtained from renewableresources. These methods require the measurement of variations inisotopic abundance between bio-based products and petroleum derivedproducts, for example, by liquid scintillation counting, acceleratormass spectrometry, or high precision isotope ratio mass spectrometry.Isotopic ratios of the isotopes of carbon, such as the ¹³C/¹²C carbonisotopic ratio or the ¹⁴C/¹²C carbon isotopic ratio, can be determinedusing isotope ratio mass spectrometry with a high degree of precision.Studies have shown that isotopic fractionation due to physiologicalprocesses, such as, for example. CO₂ transport within plants duringphotosynthesis, leads to specific isotopic ratios in natural orbio-derived compounds. Petroleum and petroleum derived products have adifferent ¹³C/¹²C carbon isotopic ratio due to different chemicalprocesses and isotopic fractionation during the generation of petroleum.In addition, radioactive decay of the unstable ¹⁴C carbon radioisotopeleads to different isotope ratios in bio-based products compared topetroleum products. The bio-based content of a product may be verifiedby ASTM International Radioisotope Standard Method D 6866. ASTMInternational Radioisotope Standard Method D 6866 determines bio-basedcontent of a material based on the amount of bio-based carbon in thematerial or product as a percent of the weight (mass) of the totalorganic carbon in the material or product. Bio-derived and bio-basedproducts will have a carbon isotope ratio characteristic of abiologically derived composition.

The class of compounds provided herein are therefore distinguishablefrom petroleum based compounds of similar or identical structure, inthat in all embodiments, the compounds provided herein have a bio-basedcontent of at least 37.5% when measured according to ASTM InternationalRadioisotope Standard Method D 6866. This minimum bio based content isachieved by recognizing that the entire 6 carbons originating from thehydroxymethyl furfural nucleus of the compounds originate from acarbohydrate, typically fructose, which is derived from plants. In someembodiments the bio based content is 100% according the ASTM standard.Compounds having a bio based anywhere between 37.5% and 100% can be madeby appropriate selection of another bio-based reagent for combining withthe HMF nucleus. For example, if the starting compound is a C₅ alkoxyether of HMF that was made by addition of a isoamyl alcohol obtainedfrom a petroleum source with the HMF from a biological source, theresulting compound of the present invention would have a bio-basedcontent of 6/11 or 54.5%. If however, the isoamyl residue was alsoobtained from a bio-based renewable resource compound such as isoamylalcohol obtained by distillation of fusel oils made during afermentation process where the carbons originate from sugar, then thecompounds of the present invention would have a bio based content of100%.

Turning now to methods of making, generally these methods include thesteps of combining a hydroxymethylfurfural ether or ester with a solventin a reaction vessel, followed by addition of a metal catalyst. Thereaction vessel is then charged with hydrogen gas. The reaction mixtureis then stirred at elevated temperature and pressure, cooled andfiltered to remove the catalyst. The solvent is then removed to yieldthe reduced product.

So there is no ambiguity, the terms “hydroxymethylfurfural ether,”“furfural ether,” and “HMF ether” are used interchangeably herein andrefer to molecules that are more technically designated R-5′ alkoxymethyl furfural ethers having the general structure:

The terms “HMF ester,” “furfural ester,” and “hydroxymethylfurfuralester” are used interchangeably herein and refer to molecules that aremore technically designated R-5′ acyl methyl furfural esters having thegeneral structure:

In each case R is an alkyl group that may be either straight chained orbranched, having from 1 to 24 carbon atoms, and may also contain oxygen,nitrogen or sulfur. Some preferred alkyl groups are the C₁ to C₅ alkylmoieties such as methyl, ethyl, n-propyl, i-propyl, i-butyl, n-butyl,i-amyl and n-amyl. These alkyl substituted HMF compounds can be derivedfrom natural bio-based sources. For example, methyl substituted HMFethers can be synthesized from methanol derived from biomassgasification. Alternatively, the C₁-C₅ alkyl groups can be obtained fromethanol and fusel oil alcohols. Fusel oil is a by-product ofcarbohydrate fermentations whose main components are isopentyl alcoholand 2-methyl-1-butanol, and to a lesser degree contains isobutylalcohol, n-propyl alcohol, and small amounts of other alcohols, estersand aldehydes. In addition, n-butanol may be derived from thefermentation of acetone/ethanol or from the catalytic condensation ofethanol.

These methods utilize metal as the catalyst for the reaction. Somepreferred metal catalysts are nickel and copper. One more preferredcatalyst is G-69B, a powdered catalyst containing 62% nickel onKieselguhr and having a zirconium promoter, available from Sud-chemieCorp. (Louisville, Ky.). The average particle size of G-69B is 10-14microns, 43% nickel by weight. Another preferred catalyst is G22/2 alsoavailable from Sud-chemie Corp. G22/2 is a barium promoted copperchromite catalyst, 39% Cu and 24% Cr. Another preferred catalyst isG-96B also available from Sud-Chemie Corp. G-96B is a nickel onsilica/alumina, 66% nickel by weight, particle size 6-8 microns. Onemore preferred catalyst G-49B available from Sud-Chemie Corp. Particlesize is 7-11 microns and 55% nickel by weight. Another preferredcatalyst is palladium on carbon, exemplified by the catalysts Pd/C.

The amount of catalyst used in the reaction is preferably sufficient toallow for efficient reduction of the starting material to the desiredproduct. Too little catalyst results in the reaction proceeding at aslow rate and may result in degradation of the starting material andproducts from elongated reaction times. The use of too much catalyst mayresult in increased costs of both catalyst and disposal of the catalyst.Generally, the preferred amount of catalyst used in the reaction is from0.5 to 15 wt/wtl %, of starting material, more preferably from about 5to 14 wt/wtl % of starting material and most preferably about 8 to 12wt/wt % of starting material. The methods can use either purified orpartially purified starting materials and result in different desiredproducts as described in more detail hereafter. Therefore, to be clear,the reference to any amount, or an amount relative to “startingmaterial” means the total amount of fufural compounds in the reactionmixture, including HMF, HMF ether or HMF esters, even though thereaction mixture may contain other compounds not pertinent to thereaction, most typically levulinic acid.

The metal catalyst may be supported with a support material. Suitablesupport materials include silicic acid, silica gel or siliceous earth,or diatomaceous earth. One preferred diatomaceous earth, kieselguhr, isa soft, chalk-like sedimentary rock that is easily crumbled into a finewhite to off-white powder. This powder has an abrasive feel, similar topumice powder, and is very light, due to its high porosity. The typicalchemical composition of diatomaceous earth is 86% silica, 5% sodium, 3%magnesium and 2% iron. Kieselguhr is a naturally occurring materialwhich consists of fossilized remains of diatoms, a type of hard-shelledalgae.

In different embodiments, reduction, or hydrogenation of HMF ethers, mayinvolve complete hydrogenation or partial hydrogenation, as depicted bythe following diagram, which depicts the partial and complete reductionproducts of HMF ethers obtained by use of the methods herein.

As used herein, complete hydrogenation of the HMF ether results inreduction of the aldehyde moiety to an alcohol group and reduction ofthe furan ring to tetrahydrofuran derivative forming a(5-alkoxymethyl)-tetrahydrofuran-2-methanol compound of the structure:

The conditions for complete reduction of the HMF ether generally requirethe use of purified HMF starting material, more active catalyst, andelevated temperatures and pressures. As used herein “purified” means thepercentage of the HMF ether as fraction of the total furfural componentsin the reaction mixture is at leas 40%. Example reaction conditions forcomplete reduction of HMF ethers are shown in Table 1:

TABLE 1 Catalyst wt/wt % catalyst to % HMF ether Temperature - pressure% HMF ether furfurals Purity time (psi) converson* Ethyl HMF 12% G69B >80% 15° C. - 4 h 1500 >98% then 200° C. - 9.5 h Ethyl HMF 12% G69B >80% 200° C. - 14 h 1350 >98% Ethyl HMF 12% G 69B >80% 250° C. -11.5 h 1150 >98% Butyl HMF 5% G 69B >95% 170° C. - 1 h 1000 >98% ButylHMF 5% G 69B >95% 200° C. - 1 h 1000 >98% Butyl HMF 1% G 69B 56% 200°C. - 5 h 1000 >98% Butyl HMF 7% Raney Ni 42% 200° C. - 5 h 1000 >98%Butyl HMF 7% Raney Ni 42% 200° C. - 5 h 1200 >98% Isoamyl HMF 10% G69B >80% 200° C. - 1 h 1400 >98% *% conversion means percent of HMFether transformed - not necessarily converted to the fully reducedspecies - the percentage of which was not quantified.

These conditions indicate that in particular, these Nickel basedcatalyst are most active and therefore most suitable for completehydrogenation of various HMF ethers to their 5′ alkoxy tetrahydrofuranderivatives and that complete hydrogenation can occur when the purity ofthe HMF ether is greater than 40%

In other embodiments of the method as described herein, partialreduction of the HMF ether involves conversion of the aldehyde to thealcohol group without hydrogenation of the double bonds in the furanring, resulting in a (5-alkoxymethyl)-furan-2-methanol compounds to forma compound of the structure:

In certain practices for partial hydrogenation purified samples of theHMF ether may be used, and reaction conditions are conducted under lesspressure, and for less time. Table 2 summarizes reaction conditionssuitable for partial reduction of purified butoxy methyl furfural (BMF)as an exemplary reactant:

TABLE 2 partially temp pressure time BMF reduced Conversion catalyst C.(psi) (h) (g/kg) BMF (g/kg) (%) 1% G69B 200 1000 2 559.6 na 75.3 1% G69B147.43 na na 6% G69B 200 800 2 700 na na 10% G22/2 190 600-900 0.5 0.28142.78 100.0 G-69B 202 1200 1 7.72 1 82.0 G-69B 201 1200 2 5.01 4.07888.3 G-69B 198 1300 3 3.04 5.323 92.9 G-69B 200 1400 4 1.68 6.228 96.1G-69B 201 1400 5 1.07 6.479 97.5 G-69B 220 1600 5.5 0.469 6.977 98.9G-49B 204 1200 1 62.14 23.09 85.5 G-49B 202 1200 2 52.89 44.68 87.6G-49B 201 1200 3 26.24 39.29 93.9 G-49B 199 1000 1 79.43 6.26 81.4 G-49B200 1000 2 40.73 31.94 90.5 G-49B 199 1100 3 24.91 37.61 94.2 G-49B 2001000 4 13.78 42.23 96.8 G-49B 200 1000 6 6.4 44.9 98.5 G-49B 200 1000 72.36 47.02 99.4

It also has been surprisingly discovered, that partial hydrogenation canadvantageously be performed using sample mixtures that less pure, forexample, mixtures containing residual reagents and products from thereaction of fructose, an acid catalyst and an alcohol that were used tosynthesize the starting HMF ether, without further purification. Suchcrude HMF ether compositions that also are suitable for partialhydrogenation typically contain on a dissolved solids basis, less than40% or more typically less than 80% of the HMF ether, less than 20% ofalkyl levulinate, less than 20% HMF, less than 25% carbohydrates, andtrace humins, the later being polymerized bi-products of the etherformation reaction.

While not being bound by theory, it is believed that more highlysubstituted furfurals such as the HMF ethers and esters used in thepresent invention, are more difficult to hydrogenate than HMF itself,and that the presence of alkyl levulinates, carbohydrates, salts, andpolymers reduces the efficiency of hydrogenation of the furan ring inthe HMF ether by occupying the catalytic sites and reacting with aportion of the hydrogen. It is surprising however, that these materialsdo not interfere with the reduction of the 2′ aldehyde to the hydroxylderivative since the amount of conversion of the HMF ether to the HMFether furan 2-methanol is nearly quantitative, with at least 60%, andmore typically at least 80% of the HMF ether being converted to thepartially reduced derivative. In addition, the partial reduction of HMFethers generally require less time and can occur using lower pressuresthan needed for the total reduction of HMF ethers. Table 3 belowillustrates a summary of exemplary conditions for partiallyhydrogenation of butoxy methyl furfural to the furan derivative usingless purified starting material:

TABLE 3 Starting purity BMF temp pressure time conversion catalyst (%)(C.) (psi) (h) (%) 10% G22/2 (Ba CuCr) 70 190 600-800 0.5 97.3 1% G69B(Ni on Zr) 15 200  800-1200 3.5 99.7 7% Raney Nickel 20 200 1000 1 99.610% G69B (Ni on Zr) 20 200 1300 3 99.8 10% G46 (Ni on 20 200 1200 2 98.7alumina/silica) 10% Pd/C 20 200 1000 3.5 99.6 3% Pd/C 20 200  500 2.599.2 5% Ru/C 20 200 1300 2.5 99.1

While Table 3 above presents summary information Table 4 below, showsactual results from a variety of test conditions with different catalystfor partial hydrogenation of BMF:

TABLE 4 partially reduced temp pressure time BMF BMF Conversion catalystC. (psi) (h) (g/kg) (g/kg) (%) 1% G69B 200 400-1200 3.5 115.32 na 1%G69B 0.4 99.7 1% G69B 200 1300 1.5 106.47 na 1% G69B 0 100.0 1% G69B 2001200 4 106.47 na 1% G69B 64.89 44.3 10% G22/2 190 900 0.5 204 10% G22/25.9 123.43 97.3 30% G96B 200 1300 1 204 30% G96B 2.22 117.03 99.0 10%G96B 200 1300 4 204 10% G96B 0.31 6.71 99.9 10% Pd/C 140 550 2 204 10%Pd/C 40.69 32.67 81.6 10% Raney Ni 200 1000 3 204 10% Raney Ni 1.2537.24 99.4 10% G96B 200 1300 3 204 10% G96B 0.36 49.19 99.8 10% G46 2001200 2 204 10% G46 2.84 322.88 98.7 10% Pd/C 200 800 1.5 204 10% Pd/C10.13 49.95 95.4 10% Pd/C 200 1000 3.5 204 10% Pd/C 0.89 62.66 99.6 3%Pd/C 204 3% Pd/C 200 585 1 25.46 53.23 88.5 3% Pd/C 202 580 2 6.93 61.996.9 3% Pd/C 201 580 2.5 1.69 57.47 99.2 3% Pd/C 200 400 3 1.3 56.2899.4 5%Ru/C 204 5%Ru/C 199 800 1.25 5.79 164.08 97.4 5%Ru/C 196 1100 22.95 203.52 98.7 5%Ru/C 199 1300 2.5 1.94 204.94 99.1 5%Ru/C 202 11003.5 2.14 165.51 99.0 204 raney Ni 199 1000 1 0.913 7.386 99.6 raney Ni202 800 2 0.143 9.09 99.9 raney Ni 201 1200 3 0.04 8.44 100.0 raney Ni200 1200 3 0.019 4.596 100.0 G-96B 200 1200 0 204 G-96B 199 1400 1 63.7730.36 70.2 G-96B 200 1400 2 29.61 68.91 86.2 G-96B 201 1400 3 12.9783.84 94.0 G-96B 200 1400 4 3.69 83.79 98.3 G-96B 200 1400 5 1.63 82.5199.3 raney Ni 203 1400 0 204 raney Ni 203 1400 1 15.8 73.27 92.9 raneyNi 201 1400 2 2.57 92.99 98.8 raney Ni 201 1400 3 0.87 81.21 99.6 raneyNi 199 1400 3.5 0.76 43 99.7 raney Ni 200 1400 5 0.4 14.52 99.8 1% G69B200 1400 1.5 150 na 1% G69B 54.37 63.8

Accordingly, based upon what has been presented herein, one skilled inthe art may determine a variety of favorable temperatures, pressures,reaction times and catalyst suitable for both full and partialhydrogenation of a variety of HMF ethers.

Because HMF is made from fructose derived from plant material, oneparticularly beneficial use of the partial and completely reduced HMFethers made according to the present invention is as a renewable biobased substitute for solvents typically made from petroleum derivedsources, particularly as substitutes for glycol ethers such ascarbiotols, which are derived from petrochemical processes. For example,(5′ butoxymethyl) tetrahydrofuran can be used as a substitute for butylcarbitol. A comparison of the structures is shown below:

Another use of the reduced alkoxy furans and tetrahydrofurans made bythe methods herein, is as a starting material for further hydrogenationof the ring structure to affect ring opening resulting in a new class ofR n-alkoxy hexane diols, which is another aspect of the presentdisclosure. This ring opening, in combination with the double-bondreducing hydrogenation step produces alkoxy-polyols that are bio-basedproducts useful for a wide variety of applications such as solvents,polymers and surfactants. Shown below are the R n-alkoxy hexane 1,2 dioland the R alkoxy hexane 1,5 diols that result from the ring openingreactions:

In a one step practice, as depicted above, these n-alkoxy hexanediolscan be made by starting with the same catalyst and the same 5′alkoxyfurfural compound used to make the partial and complete furan andtetrahydrofuran derivatives, but extending the reaction time, increasingthe temperature or increasing the pressure, or increasing the amount ofcatalyst so that hydrogen is further added to the 2′ or 5′ carbon atomsto break the ring.

One example reaction condition for this one step practice was use of aRu/C catalyst at about 1/10^(th) the weight of a purified sample of the5′alkoxy furfural compound, in an ethanol solvent and conducting thereaction at 1200 psi H₂ at 170° C. for six hours. In another exemplarypractice, still using ethanol as a solvent, the G 69B Ni catalyst withzirconium promoter was used at about 1/15^(th) the weight of thepurified 5′alkoxy furfural compound, the reaction was conducted at 1200psi at 200° C. for 5 hours. In both cases, GC/MS analysis showed atleast 20% conversion of the 5′alkoxy furfural compound to the n-alkoxyhexanediol son one of ordinary skill in the art will recognize thathigher temperatures and pressures, or prolonged times would result instill further production of the n-alkoxy hexanediols. Thoroughconversion is expected at any pressure of at least 1000 psi at anytemperature of at least 170° C. and the time can be varied as need to besufficient to make the alkoxy hexane diols without hydrogenating thealcohol groups.

In a better, two step practice, the 5′alkoxy furfural ethers are firstcompletely or partially hydrogenated to form the reduced n-alkoxy furanor tetrahydrofuran derivatives as described herein before, and thenthese compounds are subsequently purified and hydrogenated under theharsher conditions to produce the n-alkoxy hexanediols. In an exemplarypractice, the G 69B Ni catalyst with zirconium promoter was used atabout 1/15^(th) the weight of the 5′alkoxy furan derivative in a butanolsolvent, which was treated at 1200 psi for 200 C for four hours. Underthese conditions at least 70% of the partially reduced furan wasconverted to the n-alkoxy hexane diol derivative. Again, thoroughconversion is expected with any pressure of at least 1000 psi at anytemperature of at least 170° C. and the time can be varied as need to besufficient to make the alkoxy hexane diols without hydrogenating thealcohol groups.

The foregoing reaction conditions can also be used for complete andpartial reduction of HMF esters having an R-acyloxymethyl group at the5-position on the HMF ring. The acyl group may be either straightchained or branched, having from 1 to 24 carbon atoms, and may alsocontain oxygen, nitrogen, or sulfur. More typically, R is an alkyl groupof one to 5 carbons. Some preferred acyl groups are including, but notlimited to acetic, propionic, butyric, or citric. These partial andcompletely reduced acyl substituted HMF ester derivatives have thegeneral structures depicted below:

In one exemplary practice, a purified acetoxy HMF ester, where R=2, wasreduced to the partially hydrogenated furan derivative by use of 10%wt/wt G-22/2 barium promoted copper chromite catalyst at 190° C., 950psi, for one hour. These reactions are very similar to those used tomake the furan derivatives from the HMF ethers as described in greaterdetail herein before. It is clear therefore, that any of the similarreaction conditions and catalysts described for the HMF ethers can beapplied to the complete or partial reduction of HMF esters as well.

Generally, the reduction of HMF derivatives by the methods describedherein are carried out in a reaction vessel capable of withstanding hightemperatures and pressures. Typically, reaction vessels comprised ofhigh strength and high durability steel, which are resistant tocorrosion and chemical oxidation are preferred. Preferably, the reactionvessel has at least one inlet to allow for addition of hydrogen gas tothe reaction mixture before and during the reaction. A pressure gauge tomonitor the pressure of the reaction is also preferably attached to thevessel. The reaction vessel is also preferably equipped with a stirrerto allow for sufficient agitation of the reactants during the hydrogenpurging and during the reaction, although other known methods for mixingthe reaction may be employed, such as use of a magnetic stirrer. Onesuch vessel that may be used in the embodiments in the presentdisclosure is an Autoclave Engineers (Snap-tite, Inc., Erie, Pa.) highpressure reactor.

Generally, the solvent used in the reactions preferably will dissolvethe HMF derivative starting material at least at the temperature atwhich the reaction occurs. In addition, it is favorable to use a solventthat is easily removed after the reaction by common laboratory methodssuch as rotary evaporation. Some preferred solvents are methanol,ethanol, n-propanol, i-propanol, n-butanol, i-butanol, acetone, ethylacetate and the like. More preferably, the solvent is ethanol.

The amount of solvent used preferably will be sufficient to provide foradequate dissolution of the reactants, as well as to allow for thesolution to be stirred at a rate sufficient to allow the reactants tomix during the reaction. The use of too little solvent may preventadequate mixing of reactants. The use of too much solvent may requireexcessive energy to remove and increases the cost of the reaction, thetime to remove the solvent and the cost of disposal of the solvents.Generally, the reaction mixture utilizes an amount of about 1 to 50wt/vol % starting material in relation to the solvent, preferably, aboutfrom 5 to 20 wt/vol % starting material to solvent.

Generally, the temperature at which the reaction occurs determines therate of conversion of starting material, and amount of side productformation. With the present disclosure, the temperature preferably ishigh enough to allow for the reactants to interact and be converted intothe product, but not too high to cause decomposition of the reactants,products or intermediates. Preferably, the temperature range of thereaction is from about 125° C. to about 250° C. More preferably, thetemperature range is from about 170° C. to about 205° C.

Generally, the pressures at which the reactions are run are from betweenabout 500 and about 1500 psi but can be varied with selection ofreagents different catalysts, and times. In most embodiments, thepressure is between about 1000 and about 1500 psi.

Generally, the reaction time must be sufficient to allow the reaction toproceed to the desired level of completion without generation of sideproducts. Depending on specific reactants, amounts, purity of reactants,catalyst selection, and pressure, the reaction time can be from 30minutes to overnight (approximately 15 hours). In others, the reactiontime is from 30 minutes to 5 hours; and still others, the reaction timecan be from 30 minutes to 3 hours. Based on the present disclosure,those skilled in the art will readily be able to adjust the reactiontime and temperature as necessary to maximize the yield of the reactionwithout undue experimentation.

Any known method for purification of the end products may be used, suchas crystallization, distillation, solvent-solvent extraction, columnchromatography, carbon treatment, adsorption and the like. One preferredmethod is fractional distillation under reduced pressure.

While the present disclosure has described in more detail certainparticular HMF derivatives that can be made from the reduced HMF estersand ethers made according to the present teaching, there are many otherderivatives that one of ordinary skill in the art can make from suchcompounds. For example, the reduced HMF ethers and esters can beconverted into acrylates by conversion of the hydroxide grouped at theC₁ position for use as monomers in the synthesis of polymericderivatives. These HMF acrylates would have pendant furan andtetrahydrofuran substituents. The furan containing monomers may be usedfor latent cross linking or production of thermosetting thermoplastics.

For another useful derivative, the reduced or partially reduced HMFethers or esters may undergo reductive amination to produce aminesubstituted HMF ethers and esters capable of undergoing substitutionreactions typical of amines. These compounds are useful for amidesynthesis, or undergoing further amination to produce quaternaryammonium salts, which are useful for a variety of applications, such assurfactants or disinfectants. Amine-containing HMF derivatives may alsobe converted into acrylamide derivatives at the C₁ position.

For yet another useful derivative product, the reduced or partiallyreduced HMF ethers or ester s containing either a hydroxyl or aminefunctionality may be used to functionalize oxidized (acidic) starch.These functionalized starches may be utilized in a number of ways, forexample, as chelating agents for trace metal/precious metal recovery,thermally cross linkable materials, super-adsorbent articles (BioSAPswhich alternatives to petroleum based SAP, and can be used as compositesand thermoplastic materials and modifiers. An example of a syntheticroute, which uses simple acid or base catalysis to produce these typesof modified starches, is shown in FIG. 1.

Thus, the reduction of HMF derivatives by either reducing the furanring, the aldehyde moiety, or both is an important method to obtainuseful products. However, the reduction of HMF derivatives has ofteneluded researchers due to low yields and expensive reactants whichcombine to make the synthesis of derivatives of these compounds non-costeffective. Prior to the present disclosure, there was no knowncommercially viable procedure for reducing HMF derivatives.

The description provided above may better be understood by reference tothe particular examples that follow.

EXAMPLES

The following examples are offered for purposes of illustration and arenot intended to limit the scope of the invention.

Example 1 Complete Reduction of Isoamyl HMF

200 mL of purified 15% isoamyl hydroxymethylfurfural in ethanol and 100mL isoamyl alcohol was added to a 1 L Autoclave Engineers (Snap-tite.Inc., Erie, Pa.) high pressure reactor. To this was added 3.0 g G-69Bcatalyst (Sud-Chemie, Louisville, Ky.). The vessel was purged withhydrogen (4×500 psi) while continuously stirring the reaction mixture at1000 rpm. Then, hydrogen was added to the vessel to 1400 psi, and thereaction mixture was heated to 200° C. for 1 hour. The reaction mixturewas then cooled to 40° C. followed by vacuum filtration to remove thecatalyst. The filtrate was neutralized to pH 8.3 with potassiumcarbonate followed by removal of the solvent by rotary evaporation toobtain 37.24 g of a maroon oil. The oil was extracted with hexane anddecolorized with carbon. UV and GC/MS indicated complete reduction ofthe isoamnyl hydroxymethylfurfural starting material to5-isoamyloxymethyl-2-hydroxymethyl tetrahydrofuran. At this time wedidn't have a method of quantitatively analyzing the reaction mixture.The results were simply based on GC/MS, weight yield was 100%.

Example 2 Partial Reduction of Butyl HMF

750 mL of 11% butyl hydroxymethylfurfural in butanol obtained from thecrude product of the reaction of fructose and butanol under acidicconditions was added to a 1 L high pressure reactor. The crude mixturecontained 11% of the HMF ether, 2 of butyl levulinate, 3% of HMF and 70%butanol. To this was added 7.29 g G-69B nickel on kieselgur catalyst.The reaction was run in the same manner as in Example 1 except thepressure was 1200 psi and reaction time was 4 hours. GC/MS and tlcanalysis indicated partial reduction of the butyl HMF to5-butoxymethyl-2-hydroxymethylfuran. The reaction product wasfractionally distilled under reduced pressure (2-5 torr) on an oil bathheated to 150-175° C. to achieve 72% yield of5-butoxymethyl-2-hydroxymethylfuran.

Example 3 Complete Reduction of Ethyl HMF

25 mL of purified 5-ethoxymethylfurfural in 275 mL ethanol was added toa 1 L high pressure reactor. To this was added 3.09 g G-69B nickel onkieselgur catalyst. The reaction was run in the same manner as inExample 1 except the pressure was 1500 psi and reaction time was 4 hoursat 15° C. followed by 9.5 hours at 200° C. MS and NMR analysis indicatedcomplete reduction of the 5-ethoxymethylfurfural to5-ethoxymethyl-2-hydroxymethyl tetrahydrofuran.

Example 4 Complete Reduction of Ethyl HMF

This example was run under the same conditions as Example 3, except thatthe reaction time and temperature was 14 hours at 200° C. and pressurewas 1350 psi. NMR indicated complete conversion to5-ethoxymethyl-2-hydroxymethyl tetrahydrofuran.

Example 5 Complete Reduction of Ethyl HMF

This example was run under the same conditions as Example 3, except thatthe reaction time and temperature was 11.5 hours at 250° C. and pressurewas 1150 psi. NMR indicated complete conversion to5-ethoxymethyl-2-hydroxymethyl tetrahydrofuran, no method ofquantification.

As such, Examples 3-5 indicate that reduction of ethyl HMF may beachieved under mild conditions and various temperatures and pressures.

Example 6 Partial Reduction of Butyl HMF

Preparation.

A crude butyl HMF reaction mixture (143 g, 56% butyl HMF, 21% butyllevuliante, and 2% HMF) was placed in a 1 L reactor vessel with butanol(200) mL) and G-69B nickel on kieselgur catalyst (8.0 g) was added.Hydrogenation was performed at 20° C. and 1000 psi for 2 hours. Thesolution was filtered to remove the catalyst and ethanol removed byrotary evaporation to give 18.83 g of orange liquid. GC/MS data and TLCanalysis revealed partial hydrogenation of butyl HMF and 100% conversionof the BMF.

Purification.

A 113.30 g sample of the hydrogenated butyl HMF prepared as describeabove was subjected to fractional distillation under reduced pressure(2-3 torr) at an oil bath temperature of 120-165° C. A thick brightyellow oil as fraction 1 (49.98 g) contained mostly the partiallyreduced butyl HMF with some butyl levulinate. Fraction 2, a pale yellowoil (19.58 g), was pure partially reduced butyl HMF. NMR (δ, 1H); 6.20,(dd, 2.0H); 4.51, (s, 2.0H); 4.37, (s, 2.0H); 3.54, (t, 2.0H); 1.57, (m,2.0H); 1.38, (m, 2.0H); 0.95, (t, 3.0H) for total 90% yield of partiallyreduced BMF.

Example 7 Partial Reduction of Butyl HMF

A crude butyl HMF reaction mixture (11 g, 70% butyl HMF, 3% HMF, 4%butanol, and 18% butyl levulinate) was placed in a 100 mL reactor vesselwith ethanol (60 mL) and (G-69B nickel on kieselgur catalyst (0.77 g)was added. Hydrogenation was performed at 150° C. and 600 psi for 1hour. GC/MS data shown in FIG. 2 and tlc analysis revealed partialhydrogenation of butyl HMF.

Example 8 Partial Reduction of Butyl HMF

A crude butyl HMF reaction mixture (14 g, 70% butyl HMF, 3% HMF, 4%butanol, and 18% butyl levulinate) was placed in a 100 mL reactor vesselwith ethanol (50 mL) and G22/2 barium promoted copper chromite catalyst(1.0 g) was added. Hydrogenation was performed at 190° C. and 600-900psi for ½ hour. The reaction mixture was cooled and the catalyst removedby filtration. A brown liquid (58.4 g) was obtained. GC/MS and ¹H NMRdata and tlc analysis revealed partial hydrogenation of butyl HMF.Rotary evaporation provided 11.5 g of brown oil identified by ¹H NMR as80% partially reduced BMF and 20% butyl levulinate for 93% molar yieldof partially reduced BMF and 91% molar yield of butyl levulinate.

Example 9 Partial Reduction of Butyl HMF

Preparation.

A crude butyl HMF reaction mixture (64.7 g, 20% butyl HMF, 1.7% HMF, 7%butyl levulinate, and 49% butanol) was placed in a 100 mL reactor vesselwith G-22/2 barium promoted copper chromite catalyst (1.3 g).Hydrogenation was performed at 190° C. and 900 psi for ½ hour. Thereaction mixture was cooled and the catalyst removed by filtration. Abrown liquid (162.5 g) containing 123.43 g/kg partially reduced butylHMF and 50.03 g/kg butyl levulinate was obtained for quantitative yield.GC/MS shown in FIG. 3 revealed partial hydrogenation of butyl HMF.

Purification.

Approximately 20 g of the hydrogenated butyl HMF described above wassubjected to fractional distillation under reduced pressure (9.3 torr)at an oil bath temperature of 150-200° C. Four fractions were collected.¹H NMR of fraction 4 (3.2 g, thick yellow oil) indicated substantiallypure (>95%) reduced butyl HMF and ˜0.4% butyl levulinate.

Example 10 Partial Reduction of Butyl HMF

A crude butyl HMF reaction mixture (54 g, 20% butyl HMF, 1.7% HMF, 7%butyl levulinate, and 49% butanol) was placed in a 100 mL reactor vesselwith G-96B nickel on kieselgur catalyst (3 g). Hydrogenation wasperformed at 200° C. and 1400 psi for 1 hour. The reaction mixture wascooled and the catalyst removed by filtration and washed with butanol. Abrown liquid (74.1 g) containing 117.03 g/kg partially reduced butyl HMF(80% molar yield) and 32.07 g/kg butyl levulinate (63% molar yield) wasobtained. GC/MS shown in FIG. 4 reveals partial hydrogenation of butylHMF.

Example 11 Complete Reduction of Butyl HMF

A crude butyl HMF reaction mixture (25.1 g, 42% butyl HMF, 15% butyllevulinate, 18% HMF) was placed in a 100 mL reactor vessel with RaneyNickel catalyst (1.7 g) and butanol (60 g). Hydrogenation was performedat 200° C. and 1200 psi for 5 hours. The reaction mixture was cooled andthe catalyst removed by filtration. An amber liquid (92.8 g) containing8.32 g/kg completely reduced butyl HMF and 1.02 g/kg butyl levulinatewas obtained. GC/MS shown in FIG. 5 reveals complete hydrogenation ofbutyl HMF at a 90% yield.

Example 12 Complete Reduction of Butyl HMF

Pure butyl HMF (5 g) was placed in a 100 mL reactor vessel with G-69Bnickel on kieselgur catalyst (0.25 g) and ethanol (70 mL). Hydrogenationwas performed at 170° C. and 1000 psi for 1 hour. GC/MS revealedcomplete hydrogenation of butyl HMF with 100% conversion of the BMF.

Example 13 Complete Reduction of Butyl HMF

Pure butyl HMF (5 g) was placed in a 100 mL reactor vessel with G-69Bnickel on kieselgur catalyst (0.5 g) and ethanol (70 mL). Hydrogenationwas performed at 200° C. and 1000 psi for 1 hour. GC/MS revealedcomplete hydrogenation of butyl HMF.

As can be seen from Examples 6-13, the partial and complete reduction ofbutyl HMF may be achieved by careful selection of conditions andreactants.

Example 14 Reduction of Crude Butyl HMF

50.0 g of crude butyl HMF (20% BMF, 7% butyl levulinate, 2% HMF, and 49%butanol) was added to the stainless steel reaction vessel along with20.0 g of 1-butanol; (99.4+% ACS Reagent) and 2.0 g of 10% Pd/C, (Lot#C-3481, H₂O=57.67%). The reaction vessel was sealed and stirred for 2hours at 200° C. with a pressure of 800 PSI and with 610 RPM stirringrate. The reaction was then filtered and the catalyst washed withbutanol to provide 74.4 g of filtrate During the reaction, the o-ringwas compromised, and the pressure could not be held where it was set.The results indicate concentrations of butyl levulinate at 29.96 g/kg(28% molar yield), butyl HMF at 10.13 g/kg, and partially reduced butylHMF at 49.95 g/kg for a molar yield of 37% partially reduced product.

Example 15 Reduction of Crude Butyl HMF

The reaction was conducted in the manner described in Example 14 withthe following amounts of reactants: 50.1 g of BMF mixture as describedin example 14, 20 g of 1-butanol and 2.1 g of 10% Pd/C was sealed andstirred for 3.5 hours at 200° C. with a pressure of 1200 PSI and with610 RPM. The filtrate (74.2 g) contained butyl levulinate at 30.15 g/kg(28% molar yield), butyl HMF at 0.89 g/kg, and partially reduced butylHMF at 62.66 g/kg for 46% molar yield.

Example 16 Reduction of Crude Butyl HMF

The reaction was conducted in the manner described in Example 14 withthe following amounts of reactants: 54.3 g of butyl HMF (crude) asdescribed in example 14, 20.3 g of 1-butanol: 99.4+% ACS Reagent, 3.0 gof 3% Pd/C, (Süd Chemé) for 3 hours at ˜200° C. with a pressure of ˜1200PSI and with ˜575 RPM. The results show butyl levulinate at 37.78 g/kg(38% molar yield), butyl HMF at 1.30 g/kg (1% molar yield), andpartially reduced butyl HMF at 56.28 g/kg (44% molar yield).

As can be seen in Examples 14-16, the reduction of a crude mixture ofHMF ethers to the partially reduced HMF ether may be achieved under theconditions of the present method and by utilization of a crude startingmaterial.

Example 17 Reduction of Crude Butyl HMF

A crude butyl HMF reaction mixture (40 mL, 20% butyl HMF, 1.7% HMF, 7%butyl levulinate, and 49% butanol) was placed in a 100 mL, reactorvessel with G-69B nickel on kieselgur catalyst (0.8 g). Hydrogenationwas performed at 200° C. and 1400 psi for 4 hour. The reaction mixturewas cooled and the catalyst removed by filtration and washed withbutanol. A brown liquid (81.4 g) containing 61.27 g/kg partially reducedbutyl HMF (63% molar yield) and 16.5 g/kg butyl levulinate (48% molaryield) was obtained. GC/MS revealed partial hydrogenation of butyl HMF.

Example 18 Reduction of Acetoxymethylfurfural Ester (AcHMF)

Pure acetoxymethylfurfural (AcHMF, 5 g) was placed in a 100 mL reactorvessel with G-22/2 barium promoted copper chromite catalyst (0.5 g) andethanol (70 mL). Hydrogenation was performed at 190° C. and 950 psi for1 hour. GC/MS revealed partial hydrogenation of AcHMF.

As is indicated by this experiment, the preparation of the partiallyreduced form of AcHMF using catalyst and mild reaction conditions may beachieved.

Example 19 Deleted Example 20 Reduction of Partially Reduced BMF toButoxyhexane Diol

Crude 5-butoxymethyl-furan-2-methanol (3.1 g, 62%) and 1-butanol (40.0mL) were placed in a 75 mL high temperature, high pressure Parr reactor.To this reactor was added 0.35 g G 69 B nickel catalyst. The solutionwas stirred (690 rpm), hydrogen gas added and held at 1200 PSI andheated to 200° C. After four hours, the reactor was cooled and thesolution was filtered to remove the catalyst. The catalyst was washedwith butanol. The filtrate (59.9 g) was analyzed by GC/MS to showcomplete conversion of BMF and formation of butoxyhexanediol (FIG. 6).

Example 21 Deleted Example 22 Reduction of BMF to Butoxyhexane Diol

Butoxymethylfurfural (BMF) (2.0 g, 97% purity) and denatured reagentgrade ethanol (40.0 g) were placed in a 75 mL, high temperature, highpressure Parr reactor. To this reactor was added 0.20 g Ru/C (5%Ruthenium) catalyst. The solution was stirred (725 rpm), hydrogen gasadded and held at 1200 PSI and heated to 170° C. After six hours, thereactor was cooled and the solution was filtered to remove catalyst. Thefiltrate (56.6 g) was colorless. Analysis indicated complete conversionof BMF and gc/ms showed the presence of butoxyhexanediol.

Example 23 Reduction of Partiality Reduced BMF to Butoxyhexane Diol

Butoxymethylfurfural (BMF) (3.0 g, 97%) and denatured reagent gradeethanol (40.0 g) were placed in a 75 mL high temperature, high pressureParr reactor. To this reactor was added 0.20 g G 69B nickel catalyst.The solution was stirred (725 rpm), hydrogen gas added and held at 1200PSI and heated to 200° C. After five hours, the reactor was cooled andthe solution was filtered to remove catalyst. The filtrate (57.1 g) wascolorless. Analysis indicated complete conversion of BMF and gc/msshowed formation of butoxyhexanediol.

The foregoing is offered primarily for illustrative purposes. Thepresent disclosure is not limited to the above described embodiments,and various variations and modifications may be possible withoutdeparting from the scope of the present invention.

The invention claimed is:
 1. A method of making at least one desiredcompound selected from the group consisting of a(5-acyloxymethyl)-tetrahydrofuran-2-methanol compound of the formula:

and a (5-acyloxymethyl)-furan-2-methanol compound of the formula:

wherein R is an alkyl group of 1 to 5 carbons, comprising contacting asource of R-5′acyloxymethylfurfural ester with hydrogen and a catalystselected from the group consisting of: a nickel catalyst, a nickelcatalyst with a zirconium promoter, a copper chromite catalyst with abarium promoter, a ruthenium catalyst, and a palladium catalyst, at atemperature and a pressure and for a time selected to convert theR-5′acyloxymethylfurfural ester to at least one desired compound in asingle step.
 2. The method of claim 1, where the source contains atleast 40% of the R-5′acyloxymethylfurfural ester as a fraction ofdissolved solutes in the source and the desired compound formed ispredominantly the (5-acyloxymethyl)-tetrahydrofuran-2-methanol.
 3. Themethod of claim 1, where the source contains at least 40% of theR-5′acyloxymethylfurfural ester as a fraction of dissolved solutes inthe source and the desired compound formed is predominantly the(5-acyloxymethyl)-furan-2-methanol.
 4. The method of claim 1, where thesource contains less than 40% of the R-5′acyloxymethylfurfural ester asa fraction of dissolved solutes in the source and additionally containsat least 20% of a combination of alkyl levulinates and humins as afraction of dissolved solutes in the source and the desired compoundformed is predominantly the (5-acyloxymethyl)-furan-2-methanol.
 5. Themethod of claim 1, wherein the temperature is 140-250° C., the pressureis 500-1500 psi, the time is 30 min to 14 hours, the source is greaterthan 80% pure, and the reaction converts the acyloxymethylfurfural esterto the (5-acyloxymethyl)-tetrahydrofuran-2-methanol compound.
 6. Themethod of claim 1, wherein the temperature is 170-205° C., the source isless than 80% pure, the pressure is 950-1500 psi, the time is 3-7 hours,the catalyst is Raney nickel, and the reaction converts theacyloxymethylfurfural ester to the5-(acyloxymethyl)-tetrahydrofuran-2-methanol compound.
 7. The method ofclaim 1, wherein the metal catalyst is on a substrate support.
 8. Themethod of claim 1, wherein the temperature is 140-250° C., the pressureis 500-1500 psi, the time is 30 min to 8 hours, the catalyst is bariumpromoted copper chromite, and the source is less than 80% pure.
 9. Themethod of claim 1, wherein the metal catalyst comprises nickel with azirconium promoter on an inert substrate.
 10. The method of claim 1,wherein the contacting is in a solvent selected from the groupconsisting of methanol, ethanol, n-propanol, i-propanol, n-butanol,butanol, acetone, and ethyl acetate, fusel oil alcohols, and anycombinations thereof.